PEARLY NAUTILUS. 345 



being no papilla or prominence of any kind in Octopus cor- 

 responding to the osphradium of Nautilus. 



The paired Oviducts and Sperm-ducts. 



By all previous writers (Owen, Valenciennes, Van der Hoe- 

 ven^ Huxley, Keferstein, Woodward, Macdonald) the genital 

 ducts of Nautilus have been described as unpaired. A single 

 oviduct is said to be present in the female, and a single 

 sperm-duct ending in a penis-like process in the male. 

 Jhering, in an article in the 'Zeitschrift fiir wiss. Zoologie,' vol. 

 xxix, p. 589, in which an attempt is made to discuss the homo- 

 logies of the excretory organs and genital ducts of Mollusca, 

 says: "We are prevented from assuming that the relations (of 

 these two sets of organs) is the same in the Cephalopoda as in 

 the Lamellibranchia, were we otherwise inclined so to do, by 

 the fact that in Nautilus only a single oviduct exists. Until 

 we have the developmental history of Nautilus before us, there 

 is no prospect of any progress in this direction." 



Without endorsing Jhering's statements in any way upon 

 other points, we may point out that, without any reference to 

 the developmental history of Nautilus, the supposed fact that 

 in Nautilus only a single oviduct exists is demonstrated to be 

 no fact at all. 



In the female Nautilus (fig. 1) we find on the postero- 

 ventral wall of the body overhung by the mantle-skirt no less 

 than nine apertures. The central aperture is the anus (aw.). 

 The two pairs right and left of this, just in front of the hinder 

 gill-plumes, are the two openings of the great viscero-pericardial 

 chamber {vise, per.) and of the two posterior nephridial sacs 

 (nejih. jj.) respectively. Right and left, in front of the an- 

 terior gill-plumes, we find the pair of apertures appropriate to 

 the anterior nephridia {neph. a.). Nearer the middle line is 

 placed on the right side the great oviducal aperture, with 

 plaited lips {r. ov.), and at the corresponding point left of the 

 middle line is placed the aperture, which we have marked 

 /. ov. 



